Homeowners across Montezuma County received notices in the mail a few weeks ago, stating the revised value of their properties.

For the majority, values were down.

County assessor Mark Vanderpool said most residential values saw “about a 10 percent decrease”, though there were exceptions, mostly along the Dolores River.

All private properties — classified either as residential, commercial, industrial, agricultural, natural resources or vacant — are reappraised every two years. The current round of data was gathered in 2011 and the first six months of 2012. Vanderpool said the valuations could be understated, given the time delay.

“We can’t consider any sales or data after June 30, 2012. One could argue that 18-month period was perhaps the low point in the Montezuma County market,” he said. “We’re looking back in time here. I think current market value is higher than our new assessments indicate.”

The data is incomplete, he added, because all property classifications haven’t been calculated yet.

“The decrease in residential values will be largely offset by increased CO2 production by Kinder Morgan. I can’t say whether it’ll be a break-even deal or not, whether it’ll offset completely. It’s too early to say,” he said.

However, smaller taxing authorities — like school districts — could feel the effects, depending on the amount of energy extraction in their area. Mancos and Dolores school districts don’t have much energy development, for example.

During the 18-month period, 14 percent of residential sales were foreclosures, which had a “dampening effect” on all properties.

“We definitely had a two-tiered market. Foreclosures were selling at a much lower price than the other 86 percent,” Vanderpool said. “Lenders were willing to settle for lower sales prices as long as it covered their loan, and were motivated to get bank-owned assets off their books.”

Properties that did not sell during the data-collection window are assessed by comparing them to similar properties that did sell. Wildrose Appraisal Services was chosen by the Colorado Legislative Council to analyze the data.

“They examine sales prices for ranch-style homes, two-stories, log cabins, then do the same for the (corresponding) unsolds. The two numbers should be close together,” Vanderpool said.